Euroball III Data Acquisition
Online Analysis
Online analysis is defined as all the data processing that is performed by the
processor farm during the acquisition of the raw data. The processor farm can be
partitioned to allow two modes of operation:-
- Type 1. Full Online Data Processing. This has to process all the raw data
events before sending them to tape. In addition to the basic functions of
event building, data checking and event formatting it can also include
functions such as calibration, filtering and event sorting. In this case
it is necessary to consider the impact of such processing on the final
data rate. Also any errors introduced may seriously effect the correct
output of data to tape.
If required all processors in the farm can be used for this mode of operation
in which case Type 2 will not be available.
- Type 2. On request (spy) online analysis. This would always run in
conjunction with a basic Type 1 program which would just perform the
event building, data checking and event formatting steps and output the data
to tape. The data output from stage 1 would be available to the Type 2
program for calibration and event sorting. However in this mode of operation
the correct or otherwise operation of the software can have no effect on the
output of data to tape and is thus a more secure mode of operation.
In this mode of operation a predetermined percentage of events is sent to
the processors or more likely all output data and the processors just
handle as much as is possible.